- Patients must have histologically confirmed hormone receptor positive (ER and/or PR), HER2 negative, invasive breast cancer. ER, PR and HER2 measurements should be performed according to institutional guidelines, in a CLIA-approved setting in the US or certified laboratories for Non-US regions. Cut-off values for positive/negative staining should be in accordance with current ASCO/CAP (American Society of Clinical Oncology/College of American Pathologists) guidelines. Central confirmation is not required for ER, PR, or HER statuses.